 Cellular Respiration Aerobic Processes  Requires oxygen Anaerobic Processes  Do not require oxygen  Ex: Fermentation

Four stages of Cell Respiration 1.Glycolysis  Takes place in the cytoplasm 2.Formation of acetyl CoA 3.Citric Acid Cycle 4.Electron Transport Chain & chemiosmosis Steps 2-4 takes place in the Mitochondrion

Four stages of Cellular Respiration

Summary of aerobic respiration

Glycolysis: “ Sugar splitting” ◦ Glucose is split into 2 molecules of Pyruvic Acid ◦ Does not require oxygen ◦ Divided into two major phases  Energy investment phase  2 ATPs are needed to start the process  Energy capture phase  4 ATPs are produced ◦ Each glucose molecule produces net yield of 2 ATPs.

Glycolysis

Formation of Acetyl CoA ◦ The two Pyruvic Acid molecules generated in glycolysis are modified to 2 molecules of acetyl. ◦ Then, the acetyl molecules are attached to an enzyme CoA. ◦ The final product is 2 molecules of acetyl CoA.

Formation of acetyl CoA

Citric Acid Cycle ◦ For every glucose, 2 acetyl molecules enter the citric acid cycle ◦ 6 CO 2 molecules are removed & 2 ATPs are produced ◦ Many electrons are generated as a result of several chemical reactions ◦ Electrons are transported to the Electron Transport Chain to generate ATP.

Citric Acid Cycle

Electron Transport Chain ◦ Electron carrier molecules dump the electrons down the Electron Transport Chain (ETC) ◦ Electrons are then used to create bonds between ADP and Phosphate molecules to make 32 ATP molecules, through a process known as chemiosmosis

Electron transport chain

Accumulation of protons within the inter-membrane space

Electron transport and chemiosmosis

Energy yield from complete oxidation of glucose by aerobic respiration

 Many organisms depend on nutrients other than glucose  Products of protein and lipid catabolism enter same metabolic pathways as glucose

Energy from carbohydrates, proteins, and fats

Fermentation ◦ Anaerobic process that breaks down glucose into organic compounds, 2 ATP & CO 2 ◦ Takes place in the cytoplasm ◦ Two Pathways: 1.Lactic Acid Fermentation  2 ATP, Lactic Acid & 2 CO 2 2.Alcoholic Fermentation  2 ATP, Alcohol & 2 CO 2

Fermentation